Contra-angle handpiece for rotary surgical instruments, in particular in dental surgery

ABSTRACT

The invention concerns an driving appliance, called contra-angle handpiece, for surgical instruments, in particular in dental surgery, consisting of a handle ( 1 ), a neck ( 2 ) and a head ( 3 ) wherein the instrument is fixed; each of the parts of said contra-angle handpiece receiving therein a drive shaft respectively called output shaft ( 4 ) for the handle ( 1 ) and input shaft ( 8 ) for the neck ( 1 ), linked to each other by a gear train ( 21 ). The invention is characterized in that the output ( 4 ) and input ( 8 ) shafts of the appliance are mounted sliding in their respective bodies forming a sheath and maintained supported on a stop ( 11, 12 ) arranged on their corresponding sheath through a single elastic element ( 13 ) housed in the bend linking the handle ( 1 ) to the neck ( 2 ).

The present invention concerns an improvement to drive apparatuses, called contra-angle handpieces, for rotary tools used in surgery, in particular in dental surgery.

Such apparatuses called contra-angle handpieces are generally made up of an anterior part or “neck” of cylindrical/conical external shape supporting the head in which the dental instrument is fixed, and of a posterior part or “handle” having a shape which is substantially cylindrical and/or conical in revolution.

This handle comprises the mechanical connection to the dental drive motor, and, at the opposite end from the connection to the motor, the handle is connected to the neck, the axis of which, intersecting the axis of the handle, is positioned at approximately 20 degrees relative to the axis of the handle in such a way as to form a bend or contra-angle. Moreover, the axis of the dental instrument is perpendicular to the axis of the neck, the dental tool being oriented generally in the direction of the axis of the handle.

This assembly composed of handle; neck and head contains a kinematic chain, the object of which is to transmit the rotation of the motor shaft to the dental instrument, possibly with reduction or multiplication of the speed of rotation.

In view of this angle and contra-angle structure, said kinematic chain is also made up of three parts: a first part arranged in the handle, a second part in the neck, and a third part in the head. This third part is also equipped with removable or non-removable fixing means for the dental instrument, for driving it in rotation and for stopping its translation movement in the axis of the head.

Generally speaking, the rotation movement is transmitted between these different parts by way of gears having non-parallel axes whose position is of great importance, on the one hand, in terms of the useful life of the contra-angle handpiece (poor positioning being reflected in premature wear of the pinions) and, on the other hand, in terms of comfort for the patient and for the dental surgeon (poor positioning being reflected also in excessive noise), this in view of the fact that the speeds of rotation are presently 40 000 rpm.

Thus, the positioning of each part of the kinematic chain is generally such that each of the parts is fixed in the respective parts of the contra-angle handpiece (handle, neck, head) so as to form an integral body with it and thus constitute an independent subunit.

Although such apparatuses are satisfactory, the means of fixing the elements of the kinematic chain are complex and, consequently, restoring the components by replacing them is virtually impossible for non-specialists.

The object of the invention is to provide an improvement to such apparatuses which solves all or some of the aforementioned disadvantages by proposing an economical solution for assembly of the kinematic chain, also allowing, where appropriate, components to be restored by replacement by non-specialists.

To this end, the subject of the present invention is a drive apparatus, called a contra-angle handpiece, for rotary tools used in surgery, in particular in dental surgery, composed of a handle, a neck, and a head in which the tool is fixed; each of the parts of this contra-angle handpiece receives, in its interior, a drive shaft designated, respectively, as input shaft for the handle and output shaft for the neck, which shafts are connected to one another by a gear train, characterized in that the input shaft and output shaft of the apparatus are mounted sliding in their respective bodies forming a sleeve and are kept supported on an abutment, arranged on their corresponding sleeve, via a single elastic element housed in the bend connecting the handle to the neck.

According to an advantageous characteristic of the present invention, the elastic element is formed by a compression spring mounted coaxially with respect to the gear train, one of whose ends bears on the input shaft while the other end bears on the output shaft.

According to another advantageous characteristic of the present invention, the handle of the apparatus is additionally formed by a cylindrical body on which is arranged a removable and interchangeable connection piece permitting connection with different types of connectors to the drive motor.

Also according to the invention, the head of the apparatus is equipped with a quick-coupling system for the tool.

According to an embodiment of the invention, this quick-coupling system for the hand tool is composed of a clamp made of an elastic plastic material, the free end of which is able to open like a corolla by way of longitudinal grooves formed across a major part of its body and a frustoconical widening at its outer periphery intended to cooperate with a cylindrical sleeve mounted inside the body of the head, while its opposite end is fixed by way of a thread to a press button which is axially movable and returned to its rest position by a spring which thus ensures, upon return of the press button, that the clamp is tightened and, consequently, that the tool is fixed, and in that said spring bears on the rotating cylindrical sleeve made of plastic material.

According to an advantageous characteristic, the cylindrical sleeve of the quick-coupling system comprises a drive member meshing with a crankpin integral with the output shaft, thus ensuring that the rotation movement of the motor is converted into an alternating rotation movement of the tool.

According to another advantageous characteristic, the body of the neck and that of the handle are made of plastic and are connected to one another by a releasable fixing means of the thread type.

According to a variant embodiment, the body of the neck and the body of the handle are connected to one another by welding.

The abovementioned characteristics of the invention, and others too, will become clearer on reading the following description of an embodiment, reference being made to the attached drawings in which:

FIG. 1 is a longitudinal cross section through a contra-angle handpiece according to the present invention, and

FIG. 2 is a view similar to FIG. 1, illustrating an alternative embodiment.

FIGS. 1 and 2 illustrate a dental contra-angle handpiece composed of a handle 1, a neck 2, and a head 3 in which the tool is fixed; each of the parts of this contra-angle handpiece receives in its interior one or more elements of the kinematic chain for transmitting the rotation movement of a motor to the tool thus driven.

The handle 1 receives, for example, an assembly comprising a drive shaft or input shaft 4 intended to engage with the drive shaft (not shown) and, at the other end, a driving pinion 5 which transmits the rotation to the kinematic element of the neck 2.

It will be noted that, between the pinion 5 and the drive shaft, it is possible to have speed reduction or multiplication elements 6, as can be seen from FIG. 2.

The neck 2 for its part receives a transmission shaft or output shaft 8 which is provided, at one of its ends, with a driven pinion 9 meshing with the driving pinion 5 of the drive shaft 4 of the handle 1 and, at the other end, a member for transmitting movement to the head module 3, this member being of the crankpin 10 type (preferably), or a pinion or, alternatively, a friction wheel.

According to the present invention, the input shaft 4 and output shaft 8 of the apparatus are mounted slidably in their respective bodies forming a sleeve and are kept supported on an abutment 11, 12, arranged on their corresponding sleeve, via a single elastic element 13 housed in the bend connecting the handle 1 to the neck 2. Such an elastic element 13 advantageously guarantees correct positioning of the transmission elements of the kinematic chain.

It will be noted that the body of the neck 2 and that of the handle 1 are made of plastic material and are connected to one another by a releasable fixing means of the thread type or, in one variant, are welded to one another.

The elastic element 13 is formed, for example, by a compression spring mounted coaxially with respect to the driving pinion 5 and driven pinion 9 forming the gear train of the apparatus, one of its ends bearing on the input shaft 4 and the other end bearing on the output shaft 8, as is illustrated in the figures.

The handle 1 of the apparatus is in addition advantageously formed by a cylindrical body on which a removable and interchangeable connection piece 14 is arranged which permits connection with different types of connectors to the drive motor (not shown), as can be seen in the figures.

The head 3 of the apparatus is additionally provided with a quick-coupling system for the tool.

This quick-coupling system is formed by a clamp 15 made of elastic plastic material whose free end is able to open like a corolla by way of longitudinal grooves formed over a major part of its body and a frustoconical widening at its outer periphery intended to cooperate with a cylindrical sleeve 16 mounted inside the body of the head 3, while its opposite end is fixed by way of a thread to a press button 17 which is axially movable and returned to its rest position by a spring 19 which thus ensures, on return of the press button, that the clamp is tightened and, consequently, that the tool is fixed when introduced through an opening 18 formed on the head at the end remote from the press button 17. Said spring 19 bears on the rotating cylindrical sleeve 16 made of plastic material.

This cylindrical sleeve 16 additionally comprises a drive member meshing with the drive crankpin 10 integral with the output shaft 8, thus ensuring that the rotation movement of the motor is converted into an alternating rotation movement of the tool.

The functioning of the drive apparatus, called a contra-angle handpiece, for rotary tools used in surgery, particularly in dental surgery, will already be evident from the description thereof given above and will now be explained in detail.

The apparatus or contra-angle handpiece is connected to a drive motor via the appropriate connection piece 14; a first train 20 drives the input shaft 4 of the handle which, via a second train 21, drives the output shaft of the neck and, finally, via a third train 22, the rotary tool integral with the clamp mounted in the head of the apparatus.

The elastic element 13 arranged coaxially with respect to the second gear train 21 ensures correct positioning against each of the abutments 11 and 12 of the input shaft 4 and output shaft 8 of the apparatus. These abutments 11 and 12 are mounted facing each other on the body of the handle 1 and of the neck 2 in such a way that the shafts can be fitted in their respective bodies only from the area of the bend of the apparatus, namely the handle/neck connection.

From reading the above description, it will be appreciated that the apparatus according to the present invention is relatively simple to produce and permits transmission using elements which are of economical design and are easier to assemble compared to the conventional contra-angle handpiece apparatuses. In addition, such simplification affords the possibility, where necessary, of replacing used or defective parts by exchanging them, without this having to be done by specialists.

Although the invention has been described in connection with two particular embodiments, it encompasses all the technical equivalents of the means described. 

1. A drive apparatus, called a contra-angle handpiece, for rotary tools used in surgery, in particular in dental surgery, composed of a handle (1), a neck (2) and a head (3) in which the tool is fixed; each of the parts of this contra-angle handpiece receives, in its interior, a drive shaft designated, respectively, as input shaft (4) for the handle (1) and output shaft (8) for the neck (2), which shafts are connected to one another by a gear train (21), characterized in that the input shaft (4) and output shaft (8) of the apparatus are mounted sliding in their respective bodies forming a sleeve and are kept supported on an abutment (11, 12), arranged on their corresponding sleeve, via a single elastic element (13) housed in the bend linking the handle (1) to the neck (2).
 2. The drive apparatus as claimed in claim 1, characterized in that the elastic element (13) is formed by a compression spring mounted coaxially with respect to the gear train (21), one of whose ends bears on the input shaft (4) while the other end bears on the output shaft (8).
 3. The drive apparatus as claimed in claim 1 or 2, characterized in that the handle (1) of the apparatus is additionally formed by a cylindrical body on which is arranged a removable and interchangeable connection piece (14) permitting connection with different types of connectors to the drive motor.
 4. The drive apparatus as claimed in any one of the preceding claims, characterized in that the head (3) of the apparatus is equipped with a quick-coupling system for the tool.
 5. The drive apparatus as claimed in claim 4, characterized in that the quick-coupling system for the hand tool is composed of a clamp (15) made of an elastic plastic material, the free end of which is able to open like a corolla by way of longitudinal grooves formed across a major part of its body and a frustoconical widening at its outer periphery intended to cooperate with a cylindrical sleeve (16) mounted inside the body of the head, while its opposite end is fixed by way of a thread to a press button (17) which is axially movable and returned to its rest position by a spring (19) which thus ensures, upon return of the press button, that the clamp is tightened and, consequently, that the tool is fixed, and in that said spring (19) bears on the rotating cylindrical sleeve (16) made of plastic material.
 6. The drive apparatus as claimed in claim 5, characterized in that the cylindrical sleeve (16) of the quick-coupling system comprises a drive member meshing with a crankpin (10) integral with the output shaft (8), thus ensuring that the rotation movement of the motor is converted into an alternating rotation movement of the tool.
 7. The drive apparatus as claimed in any one of the preceding claims, characterized in that the body of the neck (2) and that of the handle (1) are made of plastic.
 8. The drive apparatus as claimed in claim 7, characterized in that the body of the neck (2) and the body of the handle (1) are connected to one another by a releasable fixing means of the thread type.
 9. The drive apparatus as claimed in claim 7, characterized in that the body of the neck (2) and the body of the handle (1) are connected to one another by welding. 